The girl's mother, Casey Anthony, 22, had until 9 a.m. Tuesday to accept an offer of limited immunity to help investigators in the case. Officials with the State Attorney's Office said she did not accept the offer and it has now expired.

Earlier on Tuesday, Caylee's grandmother, Cindy Anthony, left her home for an interview on NBC's "Today" show. She said she maintains her belief that her granddaughter is alive. When she returned home, there was no crowd to greet her. She was not in the mood to talk, but she did say her daughter wouldn't have accepted immunity because "she doesn't need immunity. Tell everybody to keep looking for her [Caylee]. She's alive and we need everybody calling in those tips."

"I believe Caylee is with someone Casey had trusted. I believe that Casey, you know, had been betrayed, and, you know, it's unfortunate that it's going to take the average citizen to bring Caylee back home to me alive and not the authorities," Cindy Anthony said.

Meanwhile, searchers continued to look for clues to Caylee's whereabouts.

On Monday, about 150 searchers volunteered, but by Tuesday those numbers were down.

"Once Texas EquuSearch is invited onto a case, we search, especially when we're working with law enforcement, until all leads are exhausted. If we do not find something within those parameters, we go home, we regroup and come back when more leads have bubbled up," Mandy Albritton of Texas EquuSearch said.

Representatives of EquuSearch spent Tuesday morning searching off of International Corporate Park Boulevard in East Orange County.

Searches looked mostly on foot, but some ATVs were also used to get through thick brush in wooded areas.

Rainfall has also made some locations unreachable.

"Typically to find someone, you need to replicate the conditions that existed when they went missing, and certainly we don't have the conditions on the ground that we did back in June," Albritton said.

The volunteers worked one- to two-hour rotations while searching the 25 square miles associated with leads in the investigation, always keeping safety a priority.

Members of Texas EquuSearch said they will go home and come back once the water has receded.

If convicted, Casey Anthony could face jail time. Her charges of child neglect, giving false statements to investigators, fraud, forgery, and petty theft add up to 17 years in prison if convicted.

"So these things are finally starting to come around, and we certainly expect that in short order probably there's going to be additional charges," Cmdr. Matt Irwin of the Orange County Sheriff's Office said. "At this point there is still evidence that, lab evidence, that we're not prepared to make public at this point."

George Anthony Visits Orange Co. Sheriff's Office

George Anthony made an appearance at the Orange County Sheriff's Office on Tuesday.

He pulled in to the sheriff's office parking lot pulling a billboard bearing the likeness of his missing 3-year-old granddaughter, Caylee.

He declined to talk and left a short time later after he found out the investigator he was looking for wasn't in the building.

Also On Tuesday, the State Attorney's office issued a brief release. It said the limited immunity deal they offered Casey Anthony has now expired.

From here, If convicted of all the charges she's now facing, Casey could get 17 years in prison. Investigators said they're not done looking in to her alleged economic crimes.

Despite investigators saying they believe based on lab test results that it's likely Caylee is dead, they plan to keep searching.

Detectives said there are still lab tests pending and evidence they have not made public, which could help them determine if Caylee's body may have ended up in the trunk of her mother's car.

Until detectives can get probable cause to determine if the child died and her body ended up in the trunk, sources close to the investigation told WESH 2 there won't be homicide-related charges filed.

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